Workers at an oil refinery and petrochemical site are to strike in a row over a union convenor. Unite said its members at Grangemouth in Scotland will down tools for 48 hours from 7am on Sunday 20 October over the treatment of Stephen Deans.

Unite accused Ineos of refusing to take the dispute to the conciliation service. Pat Rafferty, Unite's Scottish secretary, said: "Unite has made every effort to pull Ineos back from the brink but at every opportunity this company has kicked our proposals for peace into touch. We have pleaded with government ministers in Westminster and Holyrood and the joint owners of the Grangemouth refinery Petrochina to help rein in this reckless company before it's too late.

"A damaging strike may shut down the Grangemouth site, with serious ramifications for fuel production and supply throughout Scotland and the north of England."

Ineos recently launched a survival plan for Grangemouth, warning that the site will close by 2017 without investment and reduced costs. The company said it was losing £10m a month.

Officials said the investigation into Deans will be completed by 25 October.

Unite received an overwhelming mandate for strike action from the workforce, with 81.4% voting for walkouts and 90% for other forms of industrial action, on an 86% turnout. A work-to-rule and overtime ban has been in place this week.